LG Heat Pump Error Code t3

The T3 code indicates an error with the PWM discharge temperature sensor on the outdoor unit. The control board detected a signal voltage above 4.95V or below 0.5V, which corresponds to an open or short circuit condition in the sensor or its wiring. This error is only active when outdoor temperatures are above -10°C. The system shuts down to prevent the compressor from operating without valid discharge temperature monitoring.

No, you should not attempt to bypass or ignore the T3 error and continue running the system. The discharge temperature sensor protects the compressor from overheating. Operating without a functioning sensor removes that protection and could result in compressor damage, which is a significantly more expensive repair than addressing the sensor fault.

A power reset may temporarily clear the error code, but if the underlying fault with the sensor, connector, or wiring has not been corrected, the T3 code will return once the system restarts and attempts to read the sensor signal again. A reset alone is not a repair. The sensor circuit needs to be inspected and the fault corrected before the system will operate reliably.

A knowledgeable DIYer can start by inspecting the outdoor unit for a visibly loose or disconnected sensor connector and reseating it if needed. Testing the sensor resistance requires a multimeter and access to the resistance-temperature table for this specific sensor. However, if the sensor, wiring, or PCB needs replacement, those repairs are best handled by a certified HVAC technician, particularly because the outdoor unit involves high-voltage components.

If the fix is simply reseating a loose connector, there may be little to no parts cost, though a service call fee will still apply. If the sensor itself needs replacement, parts and labor typically range from $100 to $300 depending on your region and the technician's rates. If the outdoor PCB is at fault, repair costs can range from $300 to $700 or more including parts and labor.